Good report by 42 compiling everything we know about the injury in one place. I know many are over Gordon, but for those that care, it's a well done article. LINK
So, a year (1 year, 1 week, and 1 day . . . leap day!) seems a little long, and that is being wildly generous. This article, as do others, brings up the word arthritis. Neither Gordon nor the Hornets has ever used this term. Regardless, longer than a year to recover from a simple cleanup procedure is unreasonable. It is more reasonable to assume this other condition exists.
Gordon himself referred to a disorder, naming Andrew Bynum and Danny Granger as players with similar issues
...Andrew Bynum admits to having arthritis and to having a bone bruise that was aggravated by seemingly innocuous activity (bowling).
To be clear, arthritis can take many forms, but the most common form, osteoarthrits, is a joint disorder that results in inflammation of that joint and in connected to cartilage erosion in that joint. This erosion can be the result of wear or injury.
Danny Granger has missed significant time with patellar tendinitis. This condition affects the tendon that holds the kneecap in place. It can be present to varying degrees up to and including the rupturing of the tendon.
Both arthritis and patellar tendinitis can be scary things, arthritis moreso. Let’s look at that the Hornets and Gordon have said about the topic.